// View the content.If you now go to /first, you will see the Hello World message that is being returned from the controller.
// Create menu link.
#. In your module root, create first_module.links.menu.yml
# . Add the following:

#. Clear the cache and then you should see the menu item under configuration -> development.
#. Click on the menu item and it will take you to /first.

A custom block.

// First, we need to create a new plugin for the module.
// [Plugins] are new in Drupal 8 and provide swappable pieces of functionality.

#. To get started, create a new directory in the module’s src folder called Plugin.
This is where you can store all of your plugins for this module.

#. Then create a folder called Block. A block is a plugin type.
#. And inside the Block folder, create a file called HelloBlock.php.

#. Another new concept to Drupal that we need to use for the block is Annotations. In order for Drupal to find your block code, you need to implement a code comment in a specific way, called an Annotation.
// The full code for HelloBlock.php